Generality of Microhabitat Suitability Models for Young Colorado River Cutthroat Trout (Oncorhynchus clarki pleuriticus) across Sites and among Years in Wyoming Streams

Abstract

The generality of microhabitat-use and preference models for young-of-year (YOY) Colorado River cutthroat trout (Oncorhynchus clarki pleuriticus) was tested across sites and years among geomorphically different streams. Depths, velocities, and substrate types used by YOY cutthroat trout often differed across both sites and years. These differences could only partially be explained as a result of differences in microhabitat availability. Microhabitat-use and preference models also varied in their ability to predict the amount of suitable microhabitat across sites. Estimates of suitable microhabitat abundance differed by up to 40% when microhabitat models were randomly used across sites. However, use of a composite model resulted in estimates of suitable microhabitat abundance that differed by less than 20% of that estimated by site-specific models. Therefore, composite models developed for a region may be a useful approach for assessing microhabitat when development of site-specific microhabitat models is not possible. We recommend that further assessment of model generality be conducted for other life stages and species prior to applying microhabitat models to sites other than those where the models were developed.